1. Field of the Invention
This invention relates to circuit breakers of the type having a bimetallic thermal trip element and, more particularly, to circuit breakers for distribution transformers to control moderate power distribution on feeder circuits.
2. Description of the Prior Art
Power distribution systems include transformers in association with other protective devices for preventing or limiting power overload damage to the transformer. A completely self-protected transformer includes a circuit breaker on the secondary or low voltage side to avoid damage due to overload currents. The secondary circuit breaker disconnects the transformer from its load if the load current exceeds a predetermined rate. Such transformers are disclosed in U.S. Pat. Nos. 3,983,454 and 4,030,053.
For overload current conditions it is desirable that the circuit interruption be completed as rapidly as possible after initiation. For that purpose circuit breakers commonly incorporate a bimetal thermal trip and an instantaneous magnetic trip.